Hyalin receptor. Using 125 I-labeled membrane proteins we will search for the hyalin binding protein(s). A number of developmental predictions based on cell-hyalin behavior will serve as controls. This problem will also be examined with the cell-hyalin affinity. Cell-cell binding. Our ability to separate the enbryo into each of the three germ layers and to isolate both the extracellular matrix and the basement membrane has given us the opportunity to ask how each of these interacts with the other during development. This year we will focus on the release of PMC's from the blastoderm, the changing interaction as PMC's pass through the basement membrane, and the relative adhesiveness of ectoderm cells for hyalin, basement membrane or other cells. Ligatin. The goal is to identify which of the ligatin-associated glycoproteins are present at different times during development. Binding experiments, interruption of fertilization, passive hemaglutination, and the monoclonals will be employed in attempts to describe function of the glycoproteins.